The invention relates to improvements in threaded connections in general, and more particularly to improvements in self-locking threaded connections. Typical examples of threaded connections to which the present invention pertains are those between a spindle, bolt or screw and a single nut or between a spindle, bolt or screw and a first nut as well as a second or lock nut.
German Pat. No. 26 45 519 C2 discloses a self-locking threaded connection wherein the root of the thread of one of the mating male and female components is provided with a ramp which is inclined relative to the axis of the respective threaded component. The inclination of the ramp with reference to the axis of the respective component is constant and is in the range of 15.degree. to 45.degree., preferably between 20.degree. and 35.degree.. A drawback of the patented self-locking threaded connection is that a locking action can be achieved only when one of the mating components is acted upon by a force tending to move its thread axially relative to the other thread in a single predetermined direction. On the other hand, it is often desirable or necessary to provide a threaded connection which is self-locking in each of the two axial directions of mating threads, for example, to mount a nut on a screw bolt, feed screw or spindle in such a way that the internal thread of the nut is locked against the external thread of the male component irrespective of the direction of action of a force upon the nut or upon the male component in a sense to urge one face of the internal or external thread against the adjacent face of the other thread.
Another drawback of the patented threaded connection is that a rather large axial displacement of the male component relative to the nut or vice versa is necessary in order to achieve an acceptable self-locking action.